Asynchronous thyroid metastases of malignant melanoma: report of a rarity

Abstract

Thyroid metastasization is a very rare phenomenon with a challenging diagnosis. The incidence is 0.36% in all thyroid malignancies and it is reported it would be up to 2% after surgical specimens’ diagnosis. Thyroid metastasization of a malignant melanoma stands with an incidence of 2% in all thyroid secondarism. We report a 41-years old female with cutaneous malignant melanoma resected four years before the start of compressive symptoms secondary to multinodular goiter. Fine-needle-aspiration showed malignant cells of uncertain origin. A total thyroidectomy was performed. Histopathological examination showed multinodular metastases of malignant melanoma. Thyroid metastasis typically presents as a unifocal thyroid mass or nodule and may occur in the absence of a primary tumor diagnosis, thus leading to a misdiagnosis of thyroid primary tumor. Immunostaining and molecular testing are useful in case of doubt. Although metastases generally indicate disseminated disease, some patients may benefit from aggressive thyroid resection surgery when compared to conservative approaches. Newly-diagnosed thyroid mass in any patient with history of malignancy should raise suspicion for metastasizing. Although the overall prognosis of thyroid metastasis is poor, surgery could be an option in some cases with survival improvement or a palliative role.